Field of the Invention
The present invention relates to a fuel cell module including a fuel cell stack provided with a plurality of fuel cells for generating electrical energy by electrochemical reactions of a fuel gas and an oxygen-containing gas.
Description of the Related Art
In general, a solid oxide fuel cell (SOFC) employs a solid electrolyte. The solid electrolyte is an oxide ion conductor such as stabilized zirconia. The solid electrolyte is interposed between an anode and a cathode to form an electrolyte electrode assembly (MEA). The electrolyte electrode assembly is sandwiched between separators (bipolar plates). In use, generally, predetermined numbers of the electrolyte electrode assemblies and the separators are stacked together to form a fuel cell stack.
In comparison with the other types of fuel cells, the operating temperature of SOFC is relatively high. Therefore, it is required to maintain the SOFC at high temperature (suitable operating temperature). To this end, various proposals have been made so far.
For example, a fuel cell power generation system disclosed in Japanese Laid-open Patent Publication No. 2002-280053 is known. In this fuel cell power generation system, a plurality of solid oxide fuel cells each having a cylindrical shape with a bottom are placed in a power-generation reaction chamber. An exhaust air chamber divided by partition walls is formed at an upper position of the power generation reaction chamber, and a fuel gas chamber is formed at a lower central position of the power generation reaction chamber. At the lower position of the power generation reaction chamber, a surface combustion burner is provided around the fuel gas chamber. A heat insulating layer surrounds the power generation reaction chamber, an exhaust air chamber, and a fuel gas chamber. Further, a module container is provided around the heat insulating layer.
Further, a fuel cell apparatus disclosed in Japanese Laid-Open Patent Publication No. 2013-131329 is known. The fuel cell apparatus has a power generation chamber including a fuel cell stack accommodated at the center inside the casing. The power generation chamber is partitioned by a highly heat insulating layer, and an exhaust gas channel is provided outside of the heat insulating layer for discharging the exhaust gas produced in the power generation chamber to the outside. Further, a cathode gas channel is provided outside of the exhaust gas channel for supplying the cathode gas to the cathode of the fuel cell stack.